Full Idea
One kind of proof that is thought to be unexplanatory is the 'reductio' proof.
Gist of Idea
Reductio proofs do not seem to be very explanatory
Source
Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1)
Book Reference
Colyvan,Mark: 'An Introduction to the Philosophy of Mathematics' [CUP 2012], p.79
A Reaction
Presumably you generate a contradiction, but are given no indication of why the contradiction has arisen? Tracking back might reveal the source of the problem? Colyvan thinks reductio can be explanatory.